Data Storage Devices (DSDs) are often used to record data onto or to reproduce data from a storage media. One type of storage media includes a rotating magnetic disk, such as in a Hard Disk Drive (HDD) or a Solid-State Hybrid Drive (SSHD). In such DSDs, a head is positioned in relation to a disk to magnetically read and write data in tracks on a surface of the disk. The head is typically located on a distal end of an actuator moved by a Voice Coil Motor (VCM).
The amount of data that can be stored on a disk in a given area (i.e., an areal density) generally continues to increase with each new generation of DSDs that use a disk to store data. As the areal density of disks increase, a fly-height of the head or the distance between the head and the disk surface typically decreases to be able to read and write data in smaller or narrower tracks on the disk. For example, many modern HDDs may have a fly-height of only several nanometers. At such relatively small distances, control of the fly-height becomes more important for avoiding errors when writing and reading data due to variations in the fly-height. In many cases, the fly-height can change when a write current used to write data on the disk causes part of a slider including the head to heat up and expand or protrude toward the disk, while reading data may not cause a similar type of heating and expansion toward the disk.
In order to provide a more consistent fly-height when reading and writing data, some recent DSDs include a fly-height heater on the slider that causes a bottom surface of the slider to expand or protrude closer to the disk surface when the heater is on, and cause the bottom surface of the slider to retract away from the disk when the heater is off. The turning on of the fly-height heater may then be controlled with the writing and reading of data on the disk to provide a more consistent fly-height. For example, before writing data, the fly-height heater may be turned on at a high-power to preheat the head and then the power may be reduced as writing begins so that the fly-height of the head remains relatively the same with the heating provided by the write current during the write process. Before reading data, the fly-height heater may be turned on to a high power to preheat the head before reading and then left at the high power to maintain relatively the same fly-height throughout the read process.
However, the use of Thermal Fly-Height Control (TFC) with a fly-height heater can reduce the usable life or reliability of the head. In one aspect, the greater amount of heat applied to the slider or head and the longer duration of heating for TFC can cause the materials of the slider or head to degrade and deteriorate more quickly than if TFC was not used. In another aspect, the lowering of the fly-height can increase the likelihood of contact with a lubricant on the disk surface or the disk itself, causing increased friction or wear on the slider or head. The lowered fly-height can also increase the accumulation of disk lubricant on the slider or head due to forces from air pressure, electrostatic forces, and/or intermolecular forces. Such accumulation of lubricant on the slider or head can interfere with the reliable reading or writing of data by the head.